What does a liver with a mild starry sky appearance, echo-genic (echo-producing) portal veins, decreased parenchymal echogenicity, and mild periportal edema indicate?

Ultrasound Findings of "Starry Sky" Liver with Periportal Edema Indicate Acute Viral Hepatitis

The ultrasound findings of a liver with mild starry sky appearance, echogenic portal veins, decreased parenchymal echogenicity, and mild periportal edema most strongly indicate acute viral hepatitis. 1 This constellation of sonographic findings represents inflammation of the liver parenchyma with edema around the portal tracts.

Understanding the "Starry Sky" Appearance

The "starry sky" appearance on ultrasound is characterized by:

• Diffuse hepatic hypoechogenicity (decreased echogenicity of liver parenchyma)
• Increased conspicuity of portal triads that appear as bright echogenic foci against the dark background of edematous liver parenchyma
• Thickened portal vein walls
• Periportal edema visible as hypoechoic halos around portal veins

This pattern occurs due to:

1. Inflammatory edema causing decreased parenchymal echogenicity
2. Portal triads standing out as bright echogenic structures against the darkened background
3. Inflammation and edema surrounding portal tracts (periportal edema)

Differential Diagnosis

While acute viral hepatitis is the most common cause of this sonographic pattern, other conditions to consider include:

1. Acute viral hepatitis (most common) - Hepatitis A, B, C, D, E 1, 2, 3
2. Toxic/drug-induced hepatitis - Including alcohol-induced hepatitis 1
3. Autoimmune hepatitis - Particularly during acute flares 1
4. Ischemic hepatitis ("shock liver") - Due to hypoperfusion 1
5. Volume overload states - Congestive heart failure, fluid overload 4

Clinical Correlation

To confirm the diagnosis, the following should be evaluated:

• Liver enzymes: Acute hepatitis typically shows markedly elevated aminotransferases (AST/ALT)

  • In viral hepatitis, AST and ALT are typically elevated 5-20 times normal
  • In alcoholic hepatitis, AST:ALT ratio is typically >2 (often >3) 1
  • AST levels >500 IU/L or ALT >200 IU/L are uncommon in alcoholic hepatitis 1

• Additional imaging findings:

  • Hepatomegaly
  • Gallbladder wall thickening (75.3% of acute hepatitis cases) 1
  • Splenomegaly (52.9% of acute hepatitis cases) 1
  • Perihepatic fluid collection (may be present) 1

Diagnostic Approach

1. Laboratory testing:

   • Complete liver function tests
   • Viral hepatitis serologies (HAV, HBV, HCV, HEV)
   • Autoimmune markers if suspected (ANA, SMA, anti-LKM1, anti-SLA) 1
   • Drug and alcohol history

2. Additional imaging:

   • If diagnosis remains uncertain, consider MRI with T2-weighted sequences which will show hyperintense signal in areas of periportal edema 1, 4

3. Liver biopsy:

   • Usually not necessary for typical cases
   • Consider if diagnosis remains uncertain or autoimmune hepatitis is suspected 1

Clinical Significance and Management

The finding of a starry sky liver pattern with periportal edema should prompt:

1. Identification of the underlying cause (viral, toxic, autoimmune)
2. Supportive care for acute hepatitis
3. Serial monitoring of liver function tests
4. Treatment of the specific etiology if identified (e.g., antivirals for certain viral hepatitis)

Common Pitfalls

• Mistaking this pattern for diffuse fatty infiltration (which typically increases echogenicity)
• Failing to consider non-viral causes of acute hepatitis
• Not recognizing that severe acute hepatitis can progress to fulminant hepatic failure
• Overlooking the possibility of autoimmune hepatitis, which requires specific treatment

The starry sky appearance is a transient finding that typically resolves as the acute inflammation subsides, but monitoring for complications and progression is essential.